The present invention relates to paint supply systems, and more particularly to a apparatus and method for cleaning paint supply systems.
Paint supply systems are used in a wide variety of industries to facilitate the application of paint and other coatings. Conventional paint supply systems supply paint and other coatings from a central location to one or more painting or coating stations. A conventional paint supply system 200 is illustrated schematically in FIG. 1. As shown, the paint supply system 200 generally includes a module 202 that is connected to a paint circulation network 204. The module 202 typically includes a pump 206, a surge eliminator 208, a filter 210, a back pressure regulator 212 and a paint supply reservoir 214. The paint circulating network 204 preferably includes a network of paint heads or drops 216a–c that are connected to the module 202 by a plurality of paint lines 216.
It is often necessary to clean the paint supply system, for example, when switching between different color paints or different types of coatings. In some applications, it is not uncommon to clean the system 18–20 times in a single day. Paint supply systems are often cleaned by circulating a solvent flush through the system. This function is typically performed by replacing the paint reservoir with a solvent reservoir so that the pump 206 pumps solvent, rather than paint, through the system 200. The solvent circulates through the module 202 and paint supply lines 216 to flush paint from the system.
In some applications, a plastic plug or “pig” is used to facilitate cleaning. The pig is passed through the paint lines prior to the introduction of solvent to physically force old paint out of the lines. A conventional pig has a fixed diameter that is specifically matched to the interior diameter of the paint supply lines to be cleaned. Because of the interior configuration of the pump and other module components, the pig is typically incapable of being passed through any portion of the module. Accordingly, the pig is generally passed only through the paint lines. Even with the use of a plug, conventional cleaning systems provide only limited effectiveness.
To provide improved cleaning, one conventional system introduces air directly into the paint supply lines through the operation of an electronic control system 224 (shown in phantom lines in FIG. 1). In this system, air is injected directly into the line downstream from the pump. The air combines with the solvent and is carried through the supply lines. The air/solvent combination typically provides better cleaning performance than straight solvent flushes. Unfortunately, the electronic control system of this system is relatively expensive, placing a practical limitation on its use.